Capital Ring
The Capital Ring is a 125 kilometre trail that circumnavigates inner London, venturing no more than 16 kilometres from Trafalgar Square and no closer than 6 kilometres.
For a path that traverses such a densely populated urban area, the Capital Ring is surprisingly green. The route links many of the great city's public parks, woods, and waterways, giving access to many interesting sights and landmarks along the way and a very different view of Britain's largest metropolis than the one most tourists see. That said, there are necessarily some stretches of urban walking between the green spaces, but only a few of those could be described as lengthy.